The erythrocyte sedimentation rate (ESR) and altered lipid profile are significantly correlated with the C3 level among patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA), and ankylosing spondylitis (AS), according to new study findings presented at the 2019 American College of Rheumatology (ACR)/Association of Rheumatology Professionals (ARP) Annual Meeting. The findings suggest that the C3 level is a cardiometabolic risk factor for PsA, RA, and AS.

Patients with rheumatic conditions have an increased risk of cardiovascular disease (CVD). Some complement factors are associated with metabolic events, including metabolic syndrome.

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In a new cross-sectional study, researchers sought to evaluate the C3 levels in rheumatic diseases with increased prevalence of cardiovascular risk, as well as the relationship between C3 levels and different cardiometabolic risk factors in the different rheumatic conditions.

The researchers analyzed data of 470 patients from the Department of Rheumatology at Reina Sofia Hospital in Cordoba, Spain. Of the patients, 200 had RA; 150 had AS; 60 had PsA; and 60 had SLE. A group of 100 healthy donors were also included in the analyses.

The inflammatory markers that were measured by the researchers included C-reactive protein (CRP) level, ESR, C3 level, and insulin resistance via the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR).

The traditional CVD risk factors that were analyzed included levels of serum glucose, insulin, and low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, among others.

Results showed that all patients had significant increase in the prevalence of obesity, insulin resistance, hyperlipidemia, and hypertension. Patients with PsA had the worst cardiometabolic profile, followed by patients with RA, patients with SLE, and patients with AS.

C3 levels were significantly elevated in patients with PsA, patients with RA, and patients with AS.

The researchers observed an association between C3 levels and HOMA-IR index in all 4 groups, based on the strong correlation with insulin levels. In receiver-operating characteristic analysis, the C3 level was found to be a potential marker of insulin resistance among patients with RA, patients with PsA, and patients with SLE.

C3 levels were strongly correlated with CRP in PsA, RA, AS, and SLE. Among patients with PsA, patients with RA, and patients with AS, C3 levels were correlated with ESR and altered lipid profile.

Hard clustering analysis identified 2 distinctive phenotypes depending on the C3 levels among the patients with a rheumatic condition. Patients from one cluster presented with higher C3 levels and increased prevalence of cardiometabolic comorbidities compared with patients in a second cluster.

“Complement C3 could be a marker of [insulin resistance] in the rheumatic diseases most associated with cardiometabolic risk,” the researchers concluded. “Complement C3 could be considered a cardiometabolic risk factor in RA, PsA, and AS.”

—Melinda Stevens

Reference:

de la Rosa IA, Escudero A, Lopez-Montilla MD, et al. Complement component 3 as biomarker of cardiometabolic risk in rheumatic diseases: rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis and systemic lupus erythematosus [abstract 2132]. Arthritis Rheumatol. 2019;71(suppl 10). Presented at: 2019 ACR/ARP Annual Meeting; November 8-13, 2019; Atlanta, GA. https://acrabstracts.org/abstract/complement-component-3-as-biomarker-of-cardiometabolic-risk-in-rheumatic-diseases-rheumatoid-arthritis-ankylosing-spondylitis-psoriatic-arthritis-and-systemic-lupus-erythematosus/. Accessed November 1, 2019.